Pipelines can cover great distances in transporting a variety of products, primarily petroleum fluids such as natural gas, crude oil and refined products. The pipelines can have build-ups of impurities, such as corrosion, and foreign particles, such as dirt, on the inside of the pipeline that can hamper transmission and contaminates the product transported in the pipeline. Also, with raw materials transported on pipelines there can be naturally occurring impurities that occur and impede the transmission of the fluids. Also, increased power costs are incurred when fluid with impurities is transported through a pipeline.
There are different approaches to cleaning the inside of the pipeline while not disrupting the transmission of the fluids. One method is the use of a short cylindrical body known as a pipeline pig that has on outside diameter that fits inside the pipe. The outer surface of the pig scrapes off the build up of contaminates on the inside of the pipeline and the contaminates are carried with the fluid through the pipeline. The pigs are so commonly used that modifications in the pipelines called pig launchers and pig receiver units are built into the pipelines often every 50 to 70 miles or so. The pig launcher and receiver units are above ground and easily accessible while the pipeline may or may not be above ground. The launcher and receiver units have piping arrangements so that the pig enters the pipeline without disrupting the fluid flow and can be retrieved, cleaned and redeployed.
The contaminates in the fluid can be kept in suspension and filtered at the end of the pipeline or are carried in the fluid and can cause contamination problems at a plant receiving the product. Dirt in the fluid can clog trays in the processing of a petrochemical product. In order to remove the contaminates in the transport process, external high pressure filter units are used and the fluid is diverted from the pipeline for filtering. This process is expensive and requires special filter units along the pipeline to be assured of clean fluid transport.